> DECISIONS / BEHAVIOR

Many of these biases are studied for how they affect belief formation, business
decisions, and scientific research.

Anchoring

the common human tendency to rely too heavily, or "anchor," on one trait or piece of information when making decisions.

Attentional Bias

implicit cognitive bias defined as the tendency of emotionally salient stimuli in one's environment to preferentially draw and hold attention.

Bandwagon effect

the tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.

Bias blind spot

the tendency to see oneself as less biased than other people.

Choice-supportive bias

the tendency to remember one's choices as better than they actually were.

Confirmation bias

the tendency to search for or interpret information in a way that confirms one's preconceptions.

Congruence bias

the tendency to test hypotheses exclusively through direct testing, in contrast to tests of possible alternative hypotheses.

Contrast effect

the enhancement or diminishing of a weight or other measurement when compared with a recently observed contrasting object.

Denomination effect

the tendency to spend more money when it is denominated in small amounts (e.g. coins) rather than large amounts (e.g. bills).

Distinction bias

the tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.

Endowment effect

"the fact that people often demand much more to give up an object than they would be willing to pay to acquire it".

Expectation bias

the tendency for experimenters to believe, certify, and publish data that agree with their expectations for the outcome of an experiment, and to disbelieve, discard, or downgrade the corresponding weightings for data that appear to conflict with those expectations.

Extraordinarity bias

the tendency to value an object more than others in the same category as a result of an extraordinarity of that object that does not, in itself, change the value.

Focusing effect

the tendency to place too much importance on one aspect of an event; causes error in accurately predicting the utility of a future outcome.

Framing effect

drawing different conclusions from the same information, depending on how that information is presented.

Hostile media effect

the tendency to see a media report as being biased due to one's own strong partisan views.

Hyperbolic discounting

the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs, where the tendency increases the closer to the present both payoffs are.

Illusion of control

the tendency to overestimate one's degree of influence over other external events.

Impact bias

the tendency to overestimate the length or the intensity of the impact of future feeling states.

Information bias

the tendency to seek information even when it cannot affect action.

Interloper effect

the tendency to value third party consultation as objective, confirming, and without motive. Also consultation paradox, the conclusion that solutions proposed by existing personnel within an organization are less likely to receive support than from those recruited for that purpose.

Irrational escalation

the phenomenon where people justify increased investment in a decision, based on the cumulative prior investment, despite new evidence suggesting that the decision was probably wrong.

Loss aversion

"the disutility of giving up an object is greater than the utility associated with acquiring it".

Mere exposure effect

the tendency to express undue liking for things merely because of familiarity with them.

Money illusion

the tendency to concentrate on the nominal (face value) of money rather than its value in terms of purchasing power.

Moral credential effect

the tendency of a track record of non-prejudice to increase subsequent prejudice.

Negativity bias

the tendency to pay more attention and give more weight to negative than positive experiences or other kinds of information.

Neglect of probability

the tendency to completely disregard probability when making a decision under uncertainty.

Normalcy bias

the refusal to plan for, or react to, a disaster which has never happened before.

Omission bias

the tendency to judge harmful actions as worse, or less moral, than equally harmful omissions (inactions).

Outcome bias

the tendency to judge a decision by its eventual outcome instead of based on the quality of the decision at the time it was made.

Planning fallacy

the tendency to underestimate task-completion times.

Post-purchase rationalization

the tendency to persuade oneself through rational argument that a purchase was a good value.

Pseudocertainty effect

the tendency to make risk-averse choices if the expected outcome is positive, but make risk-seeking choices to avoid negative outcomes.

Reactance

the urge to do the opposite of what someone wants you to do out of a need to resist a perceived attempt to constrain your freedom of choice.

Restraint bias

the tendency to overestimate one's ability to show restraint in the face of temptation.

Selective perception

the tendency to reject new evidence that contradicts an established paradigm.

Social comparison bias

the tendency, when making hiring decisions, to favour potential candidates who don't compete with one's own particular strengths.

Status quo bias

the tendency to like things to stay relatively the
same.

Unit bias

the tendency to want to finish a given unit of a task or an item. Strong effects on the consumption of food in particular.

Wishful thinking

the formation of beliefs and the making of decisions according to what is pleasing to imagine instead of by appeal to evidence or rationality.

Zero-risk bias

preference for reducing a small risk to zero over a greater reduction in a larger risk.

> PROBABILITY / BELIEF

Many of these biases are often studied for how they affect business and economic decisions and how they affect experimental research.

Ambiguity effect

the tendency to avoid options for which missing information makes the probability seem "unknown."

Anchoring effect

the tendency to rely too heavily, or "anchor," on a past reference or on one trait or piece of information when making decisions (also called "insufficient adjustment").

Attentional bias

the tendency to neglect relevant data when making judgments of a correlation or association.

Authority bias

the tendency to value an ambiguous stimulus (e.g., an art performance) according to the opinion of someone who is seen as an authority on the topic.

Availability heuristic

estimating what is more likely by what is more available in memory, which is biased toward vivid, unusual, or emotionally charged examples.

Availability cascade

a self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or "repeat something long enough and it will become true").

Base rate neglect/fallacy

the tendency to base judgments on specifics, ignoring general statistical information.

Belief bias

an effect where someone's evaluation of the logical strength of an argument is biased by the believability of the conclusion.

Clustering illusion

the tendency to see patterns where actually none exist.

Conjunction fallacy

the tendency to assume that specific conditions are more probable than general ones.

Forward Bias

the tendency to create models based on past data which are validated only against that past data.

Gambler's fallacy

the tendency to think that future probabilities are altered by past events, when in reality they are unchanged. Results from an erroneous conceptualization of the Law of large numbers. For example, "I've flipped heads with this coin five times consecutively, so the chance of tails coming out on the sixth flip is much greater than heads."

Hindsight bias

sometimes called the "I-knew-it-all-along" effect, the tendency to see past events as being predictable at the time those events happened.

Illusory correlation

inaccurately perceiving a relationship between two events, either because of prejudice or selective processing of information.

Observer-expectancy effect

when a researcher expects a given result and therefore unconsciously manipulates an experiment or misinterprets data in order to find it.

Optimism bias

the tendency to be over-optimistic about the outcome of planned actions.

Ostrich effect

ignoring an obvious (negative) situation.

Overconfidence effect

excessive confidence in one's own answers to questions. For example, for certain types of questions, answers that people rate as "99% certain" turn out to be wrong 40% of the time.

Positive outcome bias

the tendency of one to overestimate the probability of a favorable outcome coming to pass in a given situation.

Pareidolia

a vague and random stimulus (often an image or sound) is perceived as significant, e.g., seeing images of animals or faces in clouds, the man in the moon, and hearing hidden messages on records played in reverse.

Pessimism bias

the tendency for some people, especially those suffering from depression, to overestimate the likelihood of negative things happening to them.

Primacy effect

the tendency to weigh initial events more than subsequent events.

Recency effect

the tendency to weigh recent events more than earlier events.

Regression toward the mean

the tendency to expect extreme performance to continue.

Stereotyping

expecting a member of a group to have certain characteristics without having actual information about that individual.

Subadditivity effect

the tendency to judge probability of the whole to be less than the probabilities of the parts.

Subjective validation

perception that something is true if a subject's belief demands it to be true. Also assigns perceived connections between coincidences.

Well travelled road effect

underestimation of the duration taken to traverse oft-traveled routes and over-estimate the duration taken to traverse less familiar routes.

> SOCIAL BIASES

Most of these biases are labeled as attributional biases.

Actor–observer bias

the tendency for explanations of other individuals' behaviors to overemphasize the influence of their personality and underemphasize the influence of their situation. However, this is coupled with the opposite tendency for the self in that explanations for our own behaviors overemphasize the influence of our situation and underemphasize the influence of our own personality.

Dunning–Kruger effect

a twofold bias. On one hand the lack of metacognitive ability deludes people, who overrate their capabilities. On the other hand, skilled people underrate their abilities, as they assume the others have a similar understanding.

Egocentric bias

occurs when people claim more responsibility for themselves for the results of a joint action than an outside observer would.

Forer effect (aka Barnum effect)

the tendency to give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. For example, horoscopes.

False consensus effect

the tendency for people to overestimate the degree to which others agree with them.

Fundamental attribution error

the tendency for people to over- emphasize personality-based explanations for behaviors observed in others while under-emphasizing the role and power of situational influences on the same behavior.

Halo effect

the tendency for a person's positive or negative traits to "spill over" from one area of their personality to another in others' perceptions of them.

Herd instinct

common tendency to adopt the opinions and follow the behaviors of the majority to feel safer and to avoid conflict.

Illusion of asymmetric insight

people perceive their knowledge of their peers to surpass their peers' knowledge of them.

Illusion of transparency

people overestimate others' ability to know them, and they also overestimate their ability to know others.

Projection bias

Self-serving bias

the tendency to claim more responsibility for successes than failures. It may also manifest itself as a tendency for people to evaluate ambiguous information in a way beneficial to their interests.

System justification

the tendency to defend and bolster the status quo. Existing social, economic, and political arrangements tend to be preferred, and alternatives disparaged sometimes even at the expense of individual and collective self-interest.

Trait ascription bias

the tendency for people to view themselves as relatively variable in terms of personality, behavior and mood while viewing others as much more predictable.

Ultimate attribution error

similar to the fundamental attribution error, in this error a person is likely to make an internal attribution to an entire group instead of the individuals within the group.